License for the tzdata information

Clive D.W. Feather clive at
Wed Apr 29 07:36:00 UTC 2009

Olson, Arthur David (NIH/NCI) [E] said:
> There's no license.

At least in English (and Scottish) law, the copyright holder of any written
material (like this) has the right to prevent any other person from copying
it. A licence is a written (and it must be written) agreement or statement
giving other people permission on stated terms (e.g. a payment per copy).

One can issue a licence that says anyone can copy it without any payment
being required provided that they retain one's name on it.

I note that the TZ data and code has several authors; in principle every
one of them would need to do this.

Again, at least in English and Scottish law, there's a doctrine of estoppel
by acquiesence. The data has been distributed without practical restriction
for so long that a court would not support a claim for infringement of
copyright at this point. However, that would not necessarily apply to new

The best solution would be to explicitly attach a Creative Commons licence
to the data and code, plus a notice that any contributions are accepted on
the terms that the licence extends to them as well.

For the record, I accept that any contribution I may have made may be
copied on the same terms as the rest of the TZ package.

Clive D.W. Feather          | If you lie to the compiler,
Email: clive at     | it will get its revenge.
Web:  |   - Henry Spencer
Mobile: +44 7973 377646

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